The present invention relates to the field of devices for locking pneumatic control valves. More particularly, this invention relates to an anti-theft device for preventing the driver controlled air brake valves of a vehicle from being released by an unauthorized person. A lockable button replaces the existing buttons on the control valves to prevent unauthorized release of the air brakes.
Semi-tractors and trailers have air brakes that the driver must release to move the vehicle. For safety reasons, the brakes are automatically applied when there is no counter-acting air pressure in the circuit. The control valve for the air brakes usually has a pair of push/pull valve stems for the semi-tractor and trailer respectively. Various devices have been tried for locking the air brake control valve or the brakes themselves. Many of these devices are costly to make and difficult to install or retrofit into a vehicle. Although mechanical devices utilizing a key-lock assembly have been proposed, such devices are unnecessarily bulky, complex, and relatively inflexible in use. Therefore, there is a need for a low-cost simple and effective lockable button device for an air brake control valve on a vehicle.
A primary objective of the present invention is the provision of an improved anti-theft device for use on semi-tractors and trailers.
Another objective of this invention is a provision of an independently lockable button device for each valve stem of an air brake control valve.
A further objective of this invention is the provision of a lockable button device that is compact and replaces the existing button on the valve stem of the air brake control valve.
Another objective of this invention is the provision of a lockable button device that readily adapts to various types of air brake control valves and control valve mounting configurations on a variety of makes and models of vehicles.
A further objective of this invention is the provision of an anti-theft device that is economical to produce, easy to use, durable and reliable in use.
These and other objects will be apparent to those skilled in the art from the drawings, as well as from the description and claims that follow.
An anti-theft device for preventing unauthorized release of the air brakes on a vehicle includes a lockable button for the valve stem for the control valve. The lockable button includes a button body, a coupling member, and a lock assembly having a latch member that selectively inserts into an annular groove on the coupling member. The coupling member is secured to move axially with the axially movable valve stem of the air brake control valve. The latch member extends into the annular groove on the coupling member to position the button body so as to limit the axial movement of the valve stem and thereby prevent the release of the air brakes.